1. Field of the Invention
The present invention relates generally to a compact size tape cassette which is smaller in size than a standard size tape cassette used widely in magnetic recording and/or reproducing apparatus such as home video tape recorders (VTRs) and hence requires an adapter when used in the home video tape recorders. More particularly, this invention relates to a compact size tape cassette having an improved pair of brake mechanisms associated with a supply reel hub and a take-up reel hub, respectively, in interlocked relation to one another to perform a reel hub releasing operation simultaneously and reliably.
2. Description of the Prior Art
As is well known, a standard size tape cassette is used widely in home video tape recorders. There has been developed a compact size tape cassette which is smaller in size than standard size tape cassette and can be recorded and reproduced by the home video tape recorder while the compatibility with the standard size tape cassette is maintained.
The compact size tape cassette can be recorded and reproduced not only by a compact video tape recorder of a construction for exclusive use with the compact size tape cassette, but also by the home video tape recorders of a construction for exclusive use with the standard size tape cassette. In the latter case, however, the compact size tape cassette must be accommodated in a tape cassette adapter having a size identical to the size of the standard size tape cassette.
Aside from the spread of the home video tape recorders, an all-in-one video camera and recorder called a VTR with camera has recently been manufactured. In the VTR with camera, the compact size tape cassette of a smaller size than the standard size tape cassette is used in order to reduce the size and weight of the VTR with camera, thereby improving the portability of the VTR with camera.
FIG. 1 of the accompanying drawings is a perspective view of a compact size tape cassette 1 shown with its guard panel or lid disposed in the open position.
The compact size tape cassette 1, as shown in FIG. 1, includes a magnetic tape 2 contained in a housing 3 composed of an upper shell 3A and a lower shell 3B assembled together, and a guard panel or lid 4 hinged to opposite side walls of the housing 3 by means of a pair of pins 10 (only one shown) so as to open and close a front opening of the housing 3.
The lower shell 3B has a cutout recess 3d through which a toothed gear 7a formed on a periphery of a lower annular flange of a take-up reel hub 7 faces to the right side wall (left-hand side in FIG. 1) of the housing 3. The recess 3d is defined when the upper and lower shells 3A and 3B are assembled. The housing 3 also has a vertical positioning groove 12 for preventing mis-loading of the compact size tape cassette 1. The positioning groove 12 is formed behind the recess 3d and extends substantially across the height of the upper and lower shells 3A and 3B.
The magnetic tape 2 extends across the front opening of the housing 3 while it is guided around left and right guide rollers 5, 5. The magnetic tape 2 is protected by the lid 4 which is normally disposed in the closed position. The lid 4 is selectively held in the open position and the closed position by means of a slider 8 which is urged forwardly into snapping engagement with a portion of the lid 4 by the force of a plate spring 11 fitted in a U-shaped groove 9 in the right side wall of the housing 3. The housing 3 further has a vertical pin-receiving hole 13 extending upwardly from the bottom of the lower shell 3B for receiving a brake-releasing pin.
When the compact size tape cassette 1 of the foregoing construction is used in a compact video tape recorder (not shown), it is loaded from an opening into the body of the compact video tape recorder until it arrives at a predetermined position in which the lid 4 is pivoted to the substantially horizontal open position such as shown in FIG. 1. Then, the compact size tape cassette 1 is lowered so that a supply reel hub 6 fits with a supply reel disc (not shown) and the toothed gear 7a on the periphery of the lower annular flange of the take-up reel hub 7 meshes with a drive gear (not shown) of the compact video tape recorder. In this instance, two pairs of vertical and oblique loading pins (not shown) and a capstan (not shown) are received in first, second and third recesses 3a, 3b and 3c, respectively, at the front side of the compact size tape cassette 1.
The compact size tape cassette 1 thus loaded can be recorded and/or reproduced by the compact video tape recorder.
On the other hand, when the compact size tape cassette 1 is used in a home video tape recorder (not shown), it is loaded by using either a tape cassette adapter which, as shown in Japanese Utility Model Publication No. 60-37739, has a size identical to the size of the standard size tape cassette, or a cassette tray on which a standard size tape cassette and a compact size tape cassette are placed.
As described above, the standard size tape cassette and the compact size tape cassette used in the video tape recorders include a housing containing a pair of reel hubs around which a magnetic tape is wound. In the recording and reproducing modes of operation, the magnetic tape wound on the supply reel hub is pulled out from the front opening of the housing, then travels along a magnetic head of the video tape recorder, subsequently returns from the front opening into the housing, and finally is wound on the take-up reel hub. In the rewinding mode of operation, the magnetic tape is fed directly from the take-up reel hub to the supply reel hub.
Each of the supply reel hub and the take-up reel hub is provided with a brake mechanism which is operative to prevent the corresponding reel hub from rotating accidentally. When the housing is subjected to an impact force or shock during transportation or handling of the tape cassette, the supply reel hub or the take-up reel hub tends to turn accidentally, thereby placing the magnetic tape into a slackened condition which will cause various deficiencies such as uneven rotation of the reel hubs, folding of the magnetic tape, and rupturing of the magnetic tape. These deficiencies can be overcome by the brake mechanism associated with the reel hubs.
FIG. 2 is a perspective view of the compact size tape cassette, with the upper shell and a part of the magnetic tape omitted for clarity.
As shown in FIG. 2, the supply reel hub 6 and the take-up reel hub 7 are received in the lower shell 3B with the magnetic tape wound around the reel hubs 6, 7. The supply reel hub 6 and the take-up reel hub 7 are provided with the corresponding ones of the brake mechanisms. The lower shell 3B includes a take-up reel stopper 14 which is cooperative with the toothed gear 7a in performing a braking operation.
The brake mechanism associated with the supply reel hub 6 includes, as shown in FIG. 3, a plurality of circumferentially spaced radial ribs 6b disposed on an under surface of a lower annular flange 6a of the supply reel hub 6, and a plurality of circumferentially spaced radial ribs 3Bc disposed on an inside surface of the lower shell 3B in confronting relation to the radial ribs 6b. The ribs 6b and the ribs 3Bc have a trapezoidal cross-section. In the assembled condition shown in FIG. 1, the supply reel hub 6 is urged downwardly toward the inside surface of the lower shell 3B by means of a reel spring (not shown) fixedly mounted on the inside surface of the upper shell 3A. In this instance, the ribs 6b on the supply reel hub 6 mesh with ribs 3Bc on the lower shell 3B to provide a braking effect on the supply reel hub 6 so that the supply reel hub 6 is normally locked in position against rotation relative to the lower shell 3B.
Thus, the brake mechanism associated with the supply reel hub 6 is composed of the plural ribs 6b and the plural ribs 3Bc.
This brake mechanism is released when, after the compact size tape cassette is loaded in a video tape recorder, a supply reel spindle of the video tape recorder or of the tape cassette adapter is inserted into the supply reel hub 6 from the bottom thereof and lifts up the supply reel hub 6 from the inside surface of the lower shell 3B, thereby disengaging the ribs 6b and the ribs 3Bc.
The brake mechanism associated with the take-up reel hub 7 includes, as shown in FIG. 4, a plurality of downwardly facing triangular teeth 14a disposed on a lower part of the take-up reel stopper 14 rotatably mounted on a support shaft or pin 3Ba upstanding from a portion of the inside surface of the lower shell 3B adjacent to the take-up reel hub 7. The teeth 14a are disposed in confronting relation to a portion of the toothed gear 7a on the periphery of the lower annular flange 7b of the take-up reel hub 7. The teeth 14a on the take-up reel stopper 14 are urged by a spring (not shown) into meshing engagement with the toothed gear 7a on the take-up reel hub 7 to provide a braking effect on the take-up reel hub 7 so that the take-up reel hub 7 is normally locked in position against rotation relative to the lower shell 3B.
Thus, the brake mechanism associated with the take-up reel hub 7 is composed of the non-illustrated spring, the triangular teeth 14a and the toothed gear 7a.
This brake mechanism is released when, after the compact size tape cassette is loaded in a video tape recorder, a brake-releasing pin (not shown) of the video tape recorder is inserted into the pin-receiving hole 13 in the lower shell 3B from the bottom thereof and lifts up the take-up reel stopper 14 from the inside surface of the lower shell 3B, thereby disengaging the teeth 14a on the take-up reel stopper 14 and the teethed gear 7a on the take-up reel hub 7.
With the spread of the VTR with camera, there has been a keen demand for a compact size tape cassette which is capable of withstanding frequent transportation and enables a long shooting time.
To cope with this demand, it is desired that the compact size tape cassette contains a magnetic tape having a base film thinner than that of the conventional magnetic tape and is so constructed as to protect the thinner magnetic tape against damage even when subjected to an impact force or shock.
However, since the braking operation of the brake mechanisms, which are associated with the supply and take-up reel hubs 6, 7 of the conventional compact size tape cassette 1 shown in FIGS. 1 through 4, relies on the force of the springs, the reel hubs 6, 7 are likely to turn against the force of the springs when an external shock is imparted on the compact size tape cassette 1.
In addition, the conventional brake mechanisms are unable to retain the magnetic tape 2 within the housing 3 when the magnetic tape 2 is pulled out while the lid 4 is being manually opened.